1. Technical Field
The present invention relates to speakers to produce sound in response to an audio signal, and also to a method of manufacturing and utilizing the same.
2. Background Art
There are known in the prior art various types of speakers having a flexible planar diaphragm mounted by its edge portions in perimeter frame. Electrically conductive elements are mounted directly to the diaphragm (e.g. in the form of wires or one or more elongate foil strips), and an amplified audio signal is directed through the conductive element or elements. Permanent magnets are placed adjacent to the diaphragm and the conductive element(s) so as to create a magnetic field to interact with the field created by the magnetic element(s). This in turn causes the diaphragm and its magnetic element(s) to vibrate and thus produce the sound.
This type of speaker is sometimes in the form of a ribbon speaker, where the diaphragm is an elongate ribbon, possibly several feet in length and only a few inches wide. Such speakers are well adapted to reproduce sound in the mid or high frequencies. In these ribbon speakers, the magnets are generally provided in the form of elongate bars positioned on opposite sides of the diaphragm.
Normally, the diaphragm will be tensioned to a moderate extent so that it has a neutral position from which it can move forwardly and rearwardly. For the speaker to faithfully reproduce the sound, it is necessary that the ribbon be properly tensioned along substantially its entire sound producing area. Further, the arrangement of the conductive element(s) relative to the location of the magnets should be such as to optimize the performance of the speaker.
A search of the patent literature has disclosed a number of patents relating generally to this type of speaker utilizing a vibrating diaphragm with conductive elements thereon, these being the following.
U.S. Pat. No. 4,319,096--Winey shows a speaker where one or more ribbon-like conductive elements are positioned in an area directly between two magnets. In one embodiment (FIG. 7), two foil strips are mounted to a diaphragm material, while in other embodiments (FIGS. 5, 6 and 8), the conductive ribbon-like element(s) itself (i.e. without being mounted to a diaphragm) creates the sound.
A rather similar arrangement is shown in U.S. Pat. No. 4,317,966--Lister.
U.S. Pat. No. 4,156,801--Whelan et al. shows a speaker where there are three permanent magnets 7 and 8, and two aluminum strips 9 which are attached to a plastic diaphragm that is in turn mounted to an edge frame. There are provided two sets of baffles 12 and 13 and 11 and 14, which are positioned to dissipate the sound which is emitted from the edge portions of the diaphragm.
U.S. Pat. No. 3,997,739--Kishikawa et al. shows a speaker where a plurality of magnets are positioned on opposite sides of the diaphragm, with conductive strips mounted to the diaphragm. A foam material 9 is positioned adjacent the diaphragm to provide damping.
U.S. Pat. No. 3,919,499--Winey shows a loud speaker having a diaphragm on which a multiplicity of conductive wires are positioned in parallel relationship.
U.S. Pat. No. 3,898,598--Asahi shows a speaker having a diaphragm of a circular configuration. In FIG. 8, the diaphragm is tensioned by an annular ring 48 having an upstanding edge that engages the diaphragm so as to tension the same.
U.S. Pat. No. 3,829,623--Willus et al. and U.S. Pat. No. 3,674,946--Winey show arrangements somewhat similar U.S. Pat. No. 3,919,499.
U.S. Pat. No. 3,141,079--Rich illustrates a speaker where the diaphragm is mounted in a perimeter frame, and there is a wire connected to the frame and arranged in a generally rectangular pattern where the rectangles formed by the wires are positioned within one another.
Also generally representative of the types of speakers are U.S. Pat. No. 4,550,228--Walker et al. and U.S. Pat. No. 4,273,968--Suyama.